Laundry Room Drain Set-Up - is it okay?

I am replumbing the laundry room in our house. I staged the fittings that I am planning on using to see if it is an okay setup. I am using a 2 inch vent (out the roof) and drain with combination tee wye fittings for the washing machine drain with a separate vent before draining vertically (also a separate sanitary tee for the sink). I am hoping this will provide excellent flow for the washing machine drain. Thanks for any pointers and checking my work/thoughts.

Just curious, is there a reason the 22.5s would cause a problem in the system or are they just pointless to have.

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Aside from being pointless, you would be creating an S-trap, which is against code. The S-trap will have a tendency to syphon the water out of the p-trap, causing sewer gases to come back into your home

If yours will be at the base of a stack (new stack in basement or bottom floor), add a cleanout like you have at the base of the stack. Are you under UPC or IPC? Under IPC, the stack has to be a minimum of 3" for a washing machine. The standpipe and p-trap are still 2". Under UPC, 2" is fine for all of it. For the standpipe, normally it is between 18" and 30" in height, but IPC allows you to go up to 42", I believe.

The combo in the vertical stack for the washer is perfectly okay, but just more costly than a sanitary tee. The vent between it and the trap prevents it from causing a 3/4 "S" trap. The washer vent only has to be 1 1/2" and the upper turn can be a regular 1/4 bend, not the long radius one you show. At the bottom is it connecting to a "floor drain" as it says, or a "drain pipe in the floor"?

hj has the best eye of anyone on the forum! Some pointed out, and I was starting to comment, on the vertical combo. Normally, that is not used because it does create an S but taking the vent off BEFORE the combo prevents the S.

As for the horizontal line, on a branch drain, there is no limit on slope, as long as it is at least 1/4" per foot. But your situation is not the branch, it is the trap arm. Dropping it too much could cause the vent take off to be below the trap seal level. That will cause siphon, and thus is prohibited. Plastic pipe joints have enough "wiggle" that you can achieve the necessary slope without using sixteenth bends.

I am talking about the drain. This is not an ice issue. The IPC requires a washing machine to connect into a 3" minimum stack or horizontal branch. Most agree this is probably overkill, but the thought is a buildup of lint over time + high pump output of newer machines could lead to backup/flooding if the line is too small.

I took a quick look online and it looks like MO is based on UPC, so the 2" will be fine in your case. Just wanted to make sure you knew about the 3" thing if you happened to be under IPC. VA is IPC based, so I have to do a 3" stack.

Thanks for all the help guys. One last question and I will be out of your hair, should you just always use a sanitary tee to intersect a vertical drain rather than a combo (even if it is vented before the vertical)?

I am in PA and believe under the IPC.
If I understand you correctly (under IPC) the verticle line above and below the san-tee must be 3" ?.....I am referencing the pic in your previous post via Terry.
Question :
I am planning a 2nd fl washing machine that was going to be vented and drained via 2" until the basement where it will tie in to a horizontal 4inch cast iron line.
So I need to run a 3" vent as well as a 3" line all the way to the 4inch main drain?
Thanks
Shawn

The vent could be 1.5" or 2". The drain would be 3". Here is what I did:

- 2" riser (~30" tall)
- 2" p-trap
- ran 2" horizontally (about 3') and connected into a 3x3x2 santee. I used a bushing on the top to reduce to 2" for vent. I then carried the 3" down until connecting into the 4" horizontal main.

It hasn't been inspected yet, but will be soon. I am working on getting the test balls and such to perform the pressure test.

See section 406 about the washing machine. You can also try talking to someone in your inspection department about it. They might be under an older version of IPC and may allow the 2" drain. For me, the 3" was just as easy as the washer is in the basement, so I didn't have to run through walls or anything. With your washer being on the 2nd floor, being able to run 2" would make things easier for you. You'll just have to see what is required locally.